Gastrointestinal histoplasmosis in an acquired immunodeficiency syndrome patient.

Learning objective was to recognize the importance of biopsy to proper management of patients with AIDS and histoplasmosis. A 37-year-old white male with untreated AIDS (CD4 count 6 cells/[micro]l and viral load >600,000) presented with a 2-month history of left sided abdominal pain and a 60 lb weight loss. A chest x-ray demonstrated calcified granulomas. A contrast CT of the abdomen demonstrated focal mural thickening at the splenic flexure with associated lymphadenopathy consistent with malignancy. Colonoscopy revealed a large, circumferentially ulcerated and friable mass in the descending colon partially occluding the lumen, which was highly suspicious for carcinoma. Biopsies demonstrated numerous yeast forms consistent with histoplasmosis capsulatum and no malignant transformation. Blood and sputum cultures as well as a bone marrow biopsy were negative for bacterial or fungal infections. The patient was begun on Amphotericin B for colonic histoplasmosis and highly active retroviral therapy for AIDS. Histoplasma capsulatum is a dimorphic fungus whose natural habitat is soil enriched with high organic content. H capsulatum is inhaled and can cause pulmonary disease in both immuno-competent and immuno-compromised individuals. Disseminated histoplasmosis arises usually when the immune system is compromised, specific T cell mediated immunity. Our patient had evidence of previous pulmonary histoplasmosis on chest x-ray but presented with disseminated colonic histoplasmosis. Gastrointestinal histoplasmosis is a relatively uncommon secondary infection in AIDS even in endemic areas. In most cases, GI malignancy is suspected due to the clinical, radiographic, and endoscopic findings and histoplasmosis is found only after biopsies are performed. In our case, secondary infection was suspected clinically but both the CT and colonoscopy favored malignancy. This case high-lights the importance of early biopsy for accurate diagnosis and proper management as H capsulatum can be the great masquerader.

Maria E. Tudor, DO, Benjamin Hayes, MD, and Mukta Panda, MD. University of Tennessee, Chattanooga, TN.